In recent years, attention has been given to sealing joints in moving vehicles, and more particularly to an apparatus for sealing a track joint in a track chain. For example, crawler tractors, such as a bulldozer, typically have a sprocket, an idler, a track chain and a number of track shoes attached to the track chain for propelling the tractor over the ground. During use of the crawler tractor the sprocket rotates and engages the track chain, thereby causing the track chain, along with the attached track shoes, to rotate around a path defined by the sprocket and the idler. The rotation of the track chain causes the track shoes to engage the ground, thereby propelling the crawler tractor over the ground to perform various work functions.
Track chains generally include a pair of parallel chains, with each parallel chain being made up of a series of entrained master links and track links. Some track chains may further include a series of pins and bushings interposed between and connected to the parallel chains. The bushings and the entrained track links cooperate to form a number of track joints which allow the necessary movement of the bushings relative to the track links during use of the track chain, for example when the track chain rotates about the sprocket and the idler. Track joints are typically equipped with a track seal assembly to keep out various corrosive and abrasive mixtures of water, dirt, sand, rock or other mineral or chemical elements to which the track chain is exposed during its use. The track seal assembly also functions to keep a lubricant within the track joint to facilitate the aforementioned relative movement of the bushings and the track links.
Metal-face seals such as DUO-CONE™ or HDDF (Heavy Duty, Dual Face) seals may be used in this application. Such seals generally comprise two metal sealing rings floating in position, two elastomeric load rings which exert uniform pressure to accurately position the metal rings and serve as the static seal between the housing and the seal ring.
The load rings also transmits the turning torque from the drive housing to the seal ring. Positive sealing contact should be provided regardless of assembly tolerance stack up, shaft deflection, axial endplay, eccentricity, or vibration. The elastomeric material is usually a silicone or nitrile rubber. Several such seals are required for each joint in common applications. For example, four such seals may be required per each track joint in track applications.